1. Field of the Invention
The present invention relates to an oscillator, in particular, an oscillator and a voltage control oscillator of the multi-space non-radiative dielectric waveguide structure, which may create waves of various frequencies through oscillator elements (e.g., Gunn Diode, etc.) and resonators built in the multi-layer structure having non-radiative dielectric waveguides of different sizes.
2. Description of Related Art
In this age of multimedia, the contents of information delivery is changing from texts to graphics, and again from graphics to moving images. Moreover, the technique of expressing the contents is improving to provide delicate and high- resolution color images. As a result, heavy loads are imposed on the computer communication system. As one way to overcome this problem, the transmission line is upgraded from T1 level to T3 level. However, this does not solve the entire problem. There may be a case where an optical fiber construction is not feasible. There may also be a necessity to support ultra-high speed information terminals. Thus, we are encountered with an urgent need to develop an ultra-high speed wireless transmitter.
In order to transmit more date in a given time, higher frequency should be used. Using higher frequency, however, entails various problems such as greater transmission loss caused by shortened wavelength. The MMIC method is one general way of processing information in a microwave band or a band above such microwave. In this method, however, the transmission loss amounts to 60 dB per 1 m at the frequency of 50 GHz, causing problems to the circuit construction.
Recently, as a way of solving the problem of transmission loss, the non-radiative dielectric waveguide is used. The non-radiative dielectric waveguide, because it is non-radiative, has a lower transmission loss rate than a microstrip circuit. With the non-radiative dielectric waveguide, a transmission line may be built more easily than with other waveguides. The non-radiative dielectric waveguide is expected to be particularly suitable for the transmission line for microwaves, in particular, for waves with wavelengths of 30 GHz or higher.
A non-radiative dielectric waveguide(2) of a size in a certain proportion of the wavelength of frequency is inserted between two parallel metal plates(1) as shown in FIG. 1. The parallel metal plates(1) must be apart from each other by at least xc2xd of the wavelength of the frequency to be used.
The size of the non-radiative dielectric waveguide to be used is determined through the following equations. When the space between the two parallel metal plates(1) is determined by a frequency, waves of such frequency may be transmitted with a low transmission loss, but if the frequency is changed, the transmission becomes impossible.
a/xcex≈0.45xe2x80x83xe2x80x83[Equation 1]                                                                        ϵ                r                            -                              1                ⁢                b                                              λ                ≈        0.4        ∼        0.6                            [                  Equation          ⁢                      xe2x80x83                    ⁢          2                ]            
In the above equations, ∈ r is the dielectric constant and xcex is the wavelength.
In order to determine the size of the dielectric block, the frequency to be used should be determined. Also, given the determined size of the dielectric block, the frequency to be used cannot be changed any more. In other words, in order to transmit waves of a particular wavelength, the size of the dielectric block and the space between two metal plates should be determined. Thus, the dielectric blocks to be inserted into a space between metal places, which space is also determined, and all the other circuits must have a single fixed size.
FIG. 2 is a partial cross-sectional diagram of an oscillator in the conventional non-radiative dielectric waveguide. A diode mount(4) with Gunn diodes(3) is installed between the parallel metal plates(1), and a metal strip line(5) connects the said diode mount(4) and the non-radiative dielectric waveguide(2), enabling signals to be transmitted.
An oscillator constructed in the above-mentioned manner has shortcomings, in that the non-radiative dielectric waveguide(2) and other components(3xcx9c5) should be of a fixed size, because size of the space between the said two metal plates(1) is already determined.
As an example, in the above equations 1 and 2, suppose that a non-radiative dielectric waveguide has a dielectric constant of 2.04 and a wavelength of 5 mm at a frequency of 60 GHz. Then the height (a) of the dielectric block turns out to be 2.25 mm and the width (b) 2.5 mm. Thus, the space between two metal plates should be 2.25 mm.
In other words, because size of the space between the two metal plates(1) is predetermined, components or non-radiative dielectric waveguides of other sizes may not be inserted into such space. The size of a non-radiative dielectric waveguide is determined by the wavelength of a frequency. If the space between two metal plates is fixed, then only the frequency with a particular wavelength may be processed. As a result, most of the conventional high frequency circuits for various frequencies may not be constructed, rendering the non-radiative dielectric waveguide less useful.
For most of the high frequency circuits, such as AM/FM receivers, TV sets, cellular phones, pagers, cordless phones, wireless devices, and receivers for satellite broadcasting, are made through the super-heterodyne method. Using such super-heterodyne method, which may enhance the amplitude by converting the frequency in the middle of signal processing, a receiver with high sensitivity may be built.
Most transmitters also conduct modulation at a low frequency for high quality modulation and increase the amplitude of the transmission frequency by multiplying the low frequency and increasing the modulation index. In the conventional non-radiative dielectric waveguides with a fixed space between two metal plates, such frequency conversion cannot be done and thus only a predetermined particular frequency may be used. Therefore, most of the high frequency circuits listed above may not be constructed.
Furthermore, in the current of high speed data communication, the size of a non-radiative dielectric waveguide should become smaller as the frequency which are used these days becomes higher. For example, the size of a non-radiative dielectric waveguide is 2.25 mmxc3x972.5 mm at the frequency of 60 GHz, but if the frequency is 120 GHz, the size should be 1.125 mmxc3x971.25 mm, the half size of that for the frequency of 60 GHz. In this case, the waveguide may be built at such size, but semiconductors comprised of other components, such as the Gunn diode, may not be reduced in size because of the internal heat and may not be inserted. For example, most of the semiconductors on the market have a diameter of 3 mm, and these cannot be inserted into the space of 1.25 mm.
An object of the present invention is to provide a high frequency oscillator and a voltage control oscillator with various diodes and non-radiative dielectric waveguides of different sizes in one package by using multi-layer structured non-radiative dielectric waveguides. The present invention would solve the problems of the conventional non-radiative dielectric waveguide oscillator that different sized diodes for the oscillator are required in order to change the oscillator frequency, because all components of the circuit should be located between two metal plates having a predetermined space between them.